This invention relates to improvements in rebound texturizing or bounce crimping of thermoplastic multifilament yarns.
The synthetic textile industry is greatly interested in texturizing synthetic thermoplastic continuous filament yarns. As produced, these yarns are relatively straight and have little bulk. It is desired that they be bulked, so that the yarns resemble more closely yarns spun from staple fiber. Customarily, these yarns are bulked by bending or crimping the individual filaments in the yarn and heat setting the yarn while the filaments are bent or crimped.
Fluid under pressure has been used extensively in the texturizing of synthetic thermoplastic yarns. See, for example, U.S. Pat. Nos. 3,097,412 and 3,373,470.
A basic advance in the texturizing of thermoplastic yarn was a technique known as a rebound or bounce crimping process which yields strikingly improved results as far as crimp quality is concerned.
Bounce crimping entails hurling yarn, by a heated fluid, through a jet in a continuous stream-like flow against a foraminous surface upon which the yarn impinges and from which the yarn instantaneously rebounds or bounces. The impact upon the foraminous surface axially buckles and crimps individual filaments of the yarn while the heated fluid passes through the foraminous surface. The texturized yarn without tension and substantially by rebound interia progresses away from the crimping zone and is retained in an essentially tensionless state until the crimp has set. Then the yarn is wound upon a storage spool or package.
Thermoplastic yarn texturized by the foregoing bounce crimping process possesses, among other things, exceptional covering capability and a high degree of resiliency as disclosed in Miller et al U.S. Pat. No. 3,686,848, issued Aug. 29, 1972.
The basic process and apparatus for practicing the process is featured in Clarkson U.S. Pat. No. 3,665,567 issued May 30, 1972. In brief summary, the Clarkson structure entails feeding a yarn through a tubular passage by a jet of steam and hurling the yarn longitudinally against a foraminous screen. The yarn is thereby crimped or texturized and rebounds laterally through a passage from which it drops down to a receiver for heat setting. The steam primarily passes through the foraminous screen and is collected, although some of the steam may pass laterally through the yarn outlet passage along with the texturized yarn.
Notwithstanding singular advantages provided the synthetic textile industry by the above-noted Clarkson bounce crimping process, room for significant advances remains.
For example, the bounce crimped yarns known heretofore have not been used widely or at all in some of the specialty yarn markets and the production of more voluminous yarns containing bounce crimped filaments wound result in an even greater area of utility in the textile industry.